Solid-back cutter-head.



No. 872,890. y DATDNTDD DEO. 3, 1907.

O. W. H. BLOOD. SOLID 'BACK CUTTER HEAD.

APPLICATION FILED NOV. 30. 1906.

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CHARLES W. H. BLOOD, OF WINTHROP, MASSACHUSETTS, ASSIGNOR TO S. A. WOODS MACHINE COMPANY, OF BOSTON, MASSACHUSETTS.

.SOLID-BACK CUTTER-HEAD.

Specification of Letters Patent.

-Patented Dec. 3, 1907.

To all whom it may concern:

Be it known that I, CHARLES W. H. BLOOD, a citizen of the United States, residing at Winthrop, in the county of Suffolk and State of Massachusetts, have invented an Improvement in Solid-Back Cutter-Heads, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

My invention is a cutter-head so constructed and arranged as to provide the strength,

recision, rigidity and endurance requisite or the highest efficiency in the modern highspeed work of wood planers.

I provide a solid back support in the cutter-head proper, for the knife or cutter, said knife being wider than usual and supported by blocksof such shape set into the cutterhead in such a manner as to cc crate with the back support of the knife in c amping the latter with absolute precision and rigidity, particularly close to the cutting edge. The back support of the knife does not engage the latter at all points, but provides separated bearing points, by which the knife is gripped to the head and is kept clamped tightly close to its cutting edge. This steadies the cutting edge and obviates the disadvantages of an uneven knife surface and prevents the admission of dirt, grit, etc. The holding block is concave longitudinally at its front side, and provided centrally at its rear side with a locating or positioning groove and tightening bolt, so that thereby it is caused to hold against the knife throughout its length, the

`gripping point or top edge of the block being below the gripping point of the head on the opposite side of the knife, thereby coperating with theplurality of bearing points of the head against said opposite side of the knife tohold the latter in absolutely immovable and unvarying position. A longitudinal grooveis provided for the heel of the .block approximately opposite the inner bearing point of the head against the knife, thereby giving still further stability. My invention comprises further constructional advantages, all of which will be pointed out more at length in the vcourse of the following description, reference being had to the accompanying drawings.

In the drawings, I have shown a preferred embodiment of my invention, Figure 1 showing a portion of the cutter-head in end elevation, partly broken away, Fig. 2 showing the clamping block in end elevation; and Fig. 3 showing a series of clamping blocks in top lan. p As each cutter-knife is similarly supported in the cutter-head it will be sufficient to describe one thereof with relation to the cutterhead. The body 1 or cutter-head proper is provided with a knife-holding recess 2 for holding the knife 3 retained by blocks 4 and bolts 5. The back wall 6 of the recess 2 does not rest vertically against the back side of the knife or cutter 3, but is provided with bearing points 7, 8, the former being opposite the heel'of the block 4 and the latter at the extreme outer end of the back wall 6 at the periphery of the cutter-head 1, so as to bear against the back of the knife or cutter 3 as close to its cutting edge as possible. Preferably, in order to get the closest and most accurate lit at the extreme outer edge 8 the face of the back wall 6 between the bearing 7 and said outer edge 8 is inclined or planed obliquely, so as to leave a cavity which narrows down gradually to the vanishing point at 8, as indicated at 9. The cavity 2 extends inwardly to a considerable depth, so as to accommodate a wide knife 3 for greater efficiency. The rear lower edge of the block 4 is provided with a rib or projection 1() fitting an undercut way or recess 11 in the head 1 and spans the distance between the wide upperA portion of the opening between the knife and a wall 12 extending outwardly from the recess 11. Preferably the construction is such that the block 4 can only be entered by sliding it in from the end, and cannot be removed vertically, this construction coperating with the remaining features in providing stability and strength. At its underside the block 4 has a clearance, preferably by being cut away as indicated at 13, so that it can move appreciably with reference to the block 4 is provided with a locating groove 15 inclined as indicated at 16 and having a Width just corresponding to the bearing end 17 of the screw, by reason of which the blocks are kept in exact position at all times balance, and hence I have provided a plurality of blocks 4 which are placed end to end in exactly the saine position in each of the holding recesses for the respective knives of the entire cutter-head, and by constructing each block so that it cannot possibly shift endwise or change its relation to the cutterhead or to the remaining blocks I have effectually eliminated the lia-bility of getting the cutter-head out of balance by the shifting of the supporting means of the knife, as heretofore provided. If the locating grooves l5 were not provided the turning movement of the screws would cause the block to crawl longitudinally with reference to the knife.

`Each block is also preferably concave lengthwise at its front-engaging side, as indicated at 18. By this means the block first bears at its ends against the knife 3 and then as it is pressed forward by the bolt 5 its middle portion is sprung forward so that the entire length of the block is held in biting engagement against the knife, whereas if the block were simply straight at its front edge the pressure of the screw or bolt 5 would cause the middle portion of the block to bite more firmly than the end portions. The top surface of the block is curved as indicated at 19 for properly discharging the chips, and its front bearing edge 2O is located to bear on the knife 3 slightly below the bearing point 8. The construction above described retains all metal possible in the head, keeps everything in even balance, grips the knife close to its cutting edge at all points, and makes it impossible for the knife to flutter in the slightest even at the highest speed. Everything is held immovably against centrifugal action and the parts are compelled to automatically true themselves to each other when clamped tightly together. In use the knife 3 and block 4 are inserte l, 1n the receiving cavities provided therefor, the knife is then adjusted to the right position and the block is forced against the knife by turning up the screw-bolt 5. As the bolt 5 presses the block forward the back of the knife is forced tightly against the two supporting points 7 and S, and as the bolt 5 is turned still tighter the block is forced strongly against the front side of the knife in gripping engagement at points intermediate the bearing points 7 and 8, thereby producing the strongest possible holding grip on the knife 3. As the bolt 5 is turned forward, the ends of the block 4 first press against the knife because of the concaved front surface of the block, and then as the block is pressed still further forward its entire surface is sprung into contact with the knife. Also because of the undercut or clearance provided at the lower side of the block the latter is free to seat itself squarely against the adjacent surface of the knife, being free to turi'i or change its position to such slight extent as may be necessary for automatically accommodating itself to the knife. As the bearing surface 7 is approximately opposite the heel of the block and the rear edge 1.0 of the latter is positively retained by the bolt-carrying wall l2 of the cutter-head, great strength, stability and firmness of grip and support are provided.

I do not intend te restrict myself in all cases to each detail nor to the precise details` herein shown, as my invention is cap able olI a variety of embodiments.

I-Iaving described my invention, what l, claim as new and desire to secure by Letters Patent is,

l. A cutter-head for wood planers and a cutter-knife, said head being provided with a longitudinal knife-supperting recess having a back wall provided with a plurality of separated bearing points in supporting engagement with the back side of said knife, said wall being out of contact with said knife excepting at said bearing points, and a clamping block supported by said recess and at its lower side having a clearaiiee above the bottom ofthe recess for permitting a slight pivotal movement of the block, and means for clamping said knife against said bearing points.

2. In a cutter-head for wood planers, a cutter-knife, a clamping block, and a tightening bolt, said head being provided with a longitudinal knife-sum)orting recess having a back wall to support the rear side of said knife, and a space in front of the knife to receive said block, and having a clearance between the bottom of the recess and the block, when the latter is in operative position, except at the rear lower edge of the block, where the latter is arranged to fulcrum against the bottom of the recess, to automatically square itself flat against the knife when moved into clamping position. by the clamping bolt.

` 3. A cutter-head for wood planers, and a cutter-knife, said head being provided with a longitudinal knife-supporting recess having a back wall provided with a plurality of bearing points in supporting engagement with the back side of said knife, said wall between said points narrowing down gradually toward the outer bearing point in a plane oblique to the knife until the cavity vanishes, and means for clamping said knife against said bearing points.

4. A cutter-head for wood planers and a cutter-knife, said head being provided with a longitudinal knife-supporting recess having a back wall provided with a plurality of izo.

bearing points in supporting engagement with the back side of said knife, said wall being out of contact with said knife excepting at said bearing points, and a clamping block constructed and arranged to permit the block to rock slightly on the head as a fulcrum for permitting it automatically to seat itself squarely against the front side of the knife, and a screw-bolt for clamping said knife and block in immovable' position.

5. A cutter-head for wood planers and a cutter-knife, said head being provided with a longitudinal knife-supporting recess having a back wall provided with a plurality of bearing points in supporting engagement with the back side of said knife, said wall being out of contact with said knife excepting at said bearing points, a clamping block having its front side adapted to fit against the front side of said knife, with a clearance between the block and bottom of the recess except at the rear lower edge of the block where 'the latter fulcrums on the recess, said block having an oblique locating groove in its rear side, and a screw-bolt mounted in the cutter-head back of the block obliquely to the plane of the knife, snugly fitting at its outer end against said locating groove for clamping the block and knife in immovable position and maintaining the block in unvarying longitudinal position.

6. A cutter-head for wood planers, having alongitudinal recess provided with a knifesupporting wall at its rear side and a blocksupporting wall at its opposite side, said block-supporting wall terminating at its inner end in a way undercut in the form of a rentrant angle at yan angle to the rest of the wall, a knife to fit against said knifesupporting wall, a block occupying said recess between said knife and said block-supporting wall, said blockhaving at its rear lower edge a rib rojecting angularly beyond the adjacent side of the block to occupy said undercut way, and tightening means extending through said head against said side for clamping the block and knife in immovable position in said recess.

7. A cutter-head for wood planers, having a longitudinal recess provided with a knifesupporting wall at its rear side, a knife supported by said wall, a series of short blocks placed end to end, for holding said knife, each block having its front side slightly concave longitudinally, and arranged to fulcrum against the opposite side of the recess to automatically square itself flatagainst the knife, and clamping'means centrally engaging the back side of each of said clamping blocks for 'squaring the block as aforesaid and at the same time springing the middle portion of the block forward into uniform pressing engagement with said knife at all points.

8. A cutter-head for wood planers, having `a longitudinal recess provided with adeep extension at one side thereof, a knife extending vertically in said recess at said side thereof, and a clamping block occupying the upper wide portion of the recess in clamping engagement with said knife, said knife extending normally below said clamping block into said extension and the block being capable of swinging on its rear bottom corner as a fulcrum bearing against the head to automatically square itself against the knife.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

CHARLES W. H. BLOOD. 

